Indicator tubes



Sept. 29, 1959 J, H, Mc Y r 2,906,906

INDICATOR TUBES Filed May 22, 1958 m m v A M R O T m s F- R Pig. 4

IIIII INVENTOR. JOHN H Ma C/IULE) BY JOHN R. BETHAE ATTORNEY UnitedStates PatentO INDICATOR TUBEQ John H. McCauley, Elizabeth, and John R.Bethke, Martinsville, N.J., assignors to Burroughs Corporation, Detroit,Mich., a corporation of Michigan Application May 22, 1958, Serial No.737,036

' 8 Claims. c1. sis-109.5

This invention relates to gaseous indicator glow tubes and,particularly, to tubes of this type which contain a plurality ofindicating glow cathodes.

Tubes of the type contemplated by the present invention are particularlysuited for use with circuits which utilize binary principles ofoperation. Binary counters which use a series of interconnectedflip-flop circuits are of this type. Such decade counters generallyemploy a matrix for translating a signal representing a binary number toa signal representing a decimalor other number equivalent of the binarynumber. Up to the present time, counters of this type have not had acompletely satisfactory arrangement for providing direct readout of acount made by the counting circuit.

Accordingly, one object of the invention is to provide animprovedcathode indicator glow tube.

Another object of the invention is to provide an improved cathodeindicator glow tube particularly suited for use in conjunction withbinary-type counting circuits and, for providing a direct visiblereadout therefrom.

In brief, the principles and objects of the invention are embodied in atube which comprises a gas-filled envelope containing a plurality ofcathode glow electrodes. If, for example, the tube is to be used in adecade counter, it contains cathodes in the form of numerals to "9. Thecathode glow electrodes are arranged in groups with each group havingits own anode and with the groups separated from each other by asuitable barrier or shield. For use in a binary-coded system, thecathode electrodes are arranged in v two groups with theodd-numberelectrodes in one group and the even-number electrodes in the othergroup. Other combinations of cathode electrodes may be made as requiredbya particular code or circuit application. In addition, more than twogroups of electrodes may be provided so that a simultaneous readout of aplurality of characters may be achieved.

In operation of a tube of the type described above, a

2,906,906 Patented Sept. 29, 1959 embodying the invention adapted toprovide a multiple numeral readout.

Referring to the drawings, one form of a gaseous indicator glow tube 10embodying the invention includes an envelope 12 which has been evacuatedof air and filled with an ionizable gas such as neon or the like at asuit able pressure, for example, in the range of about to about 120 mm.Hg. The envelope includes a base portion or stem 14 through whichinsulation-coated metal base pins 16 extend and by means of whichelectrical connection is made to suitable external electrical circuitelements. Two diametrically opposed pins 16 are suitably elongated toreceive and support the various electrode elements of the tube. Theenvelope 12 also includes a transparent viewing window 20'through' whichglowing indicator cathode electrodes 22may be viewed. The viewing windowmay be plane or curved and'is oriented substantially transverselyto thevertical or longitudinal axis of the tube. A sealed-off exhausttubulation (not shown) is provided in the stem 14. i

The electrode elements of the tube include the following. A generallycup-shaped electrode 24 is provided to contain the other electrodeelements. Thecup-shaped electrode 24 is made of conductive ornon-conductive material, depending on how it is to be used, and may beimperforate, in mesh form, or in any other suitable form. The cupelectrode serves to shield the cathode electrodes 22 and to limitcathode glow to the main viewable body portions of the cathode numbersthem selves. The cup also prevents the cathode pins and connecting leadsfrom glowing spuriously and from having metal sublimed thereon. The cupelectrode 24 includes a base 26 and a peripheral wall '28. The base 26is oriented transverse to the longitudinal axis of the tube 10. The cup24 rests on, and is insulated from, the pins 16 by an insulating disk 30of mica or the like. The pins 16' pass through suitable apertures in thebaseof I the cup and in the mica disk. Although the cup24 is a I areshown in Fig. 1.

single cathode in a group. may be, caused to glow by the application ofthe proper energizing voltage between the selected cathode and the anodeassociated with this cathode. The shield prevents interaction betweenthe groups of electrodes and spurious glow of a cathode other than theselected cathode.

According to another aspect of the invention, multiple groups ofcathodes are provided in a single envelope and are electricallyconnected so that a plurality of cathodes may be caused to glow at thesame time to provide a multiple numeral readout.

The invention is described in greater detail by reference to the singlesheet of drawings wherein:

Fig. 1 is a perspective view of a tube embodying the invention;

desirable tube element, it is not required, and the tube 10 may be madeto operate without it. I

The cathode indicator electrodes 22 of the tube 10 may takesubstantially any desired shape; for example; they may be numbers,letters, or the like. In one form of the tube 10 wherein the cathodeelements are numbers, ten of such elements are provided, including thenumbers 0 to "9. These are shown schematically in Fig.2. For purposes ofsimplicity, only two cathodes The cathode elements 22 are made of anysuitable metal, for example, stainless steel, alumif num, Nichrome,molybdenum, or the like; and they may be made in any suitable fashion,for example, by etching, stamping, formed wire, or the like.

The cathode electrodes 22 are mounted in a vertical stack having avertical axis and are oriented substantially 7 material and are suitablydisplaced laterally with respect Fig. 2 is a schematic representation ofthe tube of Fig. 1 E

1 and a circuit in which it may be operated;

Fig. 3 shows the tube of Fig 2 and a schematic representation of asystem in which i-tmay be used; and

Fig. 4 is a schematic representation or 'a modified tube to each otherso that each one is not obstructed by the others and each issubstantially completely visible through tabs *32 (only one is shown),at least two in number.

The tube shown in Fig. 1'

and oriented diametrically opposite each' other, by means of which thecathodes are mounted and supported on the pins 16. Each cathode isprovided with a suitable lead wire (not shown) extending from one of theapertnred tabs thereof to one of the pins 16 within the envelope. Onegroup of cathodes, for example, the odd-numbers, is rriollnted'first onthe pins or posts 16'; These cathodes are mounted one above the otherwith their surfaces oriented parallel to each other and transverse tothe vertical' axis ofthe tube and facing the viewing end of theenvelope. The cathodes are mounted with suitable insulating spacers 34between each one, the spacers being larger than theapertured tabs andhaving sufficient surface area' to cover and insulate the tabs toprevent them from glowing.

Next, three screen electrodes 36, 38, and 40 are mounted above theodd-number cathodes, the screens being parallel to. each other andinsulated f rom each other by suitable insulating spacers 34. Thescreens also have suitable apertured tabs for mountingon the pins 16'and lead wires for making suitable electrical connections to pins 16.The first screen 36 comprises an anode for the odd-number cathodes, andthe third screen 40. is an anode for the even-number cathodes. Themiddle screen 38 is a shield which separates the two groups ofelectrodes from each other. The even-number cathodes are mounted abovethe anode screen 40, and finally a top screen 42 caps the stack ofelectrode elements. The top screen is used to prevent sublimation ofmetal from the cathodes onto the viewing window 20 which might therebybecome opaque.

If the. tube 10' is to be used in a binary-type decade counter usingflip-flop circuits, then the cathodes are connected together in pairs,the pairs comprising, for example, zero and one, two and three, four andfive, six and seven, eight and nine. The, interconnections may be madein any suitable fashion; for example, each cathode 22 may be connectedto a pin 16 and the appropriate pins may be connected together insidethe envelope or outside the envelope. In another arrangement, the leadsfrom each two cathodes to be connected together may be secured directlyto the same pin inside the envelope. In another arrangement, the socketto be used with the tubes may be wired to provide the desired cathodepairs.

Each anode screen 36 and 40 is connected to its own pin lead 16, just asthe cathodes are. The shield screen electrode 38 may also be connectedto a pin 16 and may be operated electrically neutral or at some suitablepo tential. The cup 24 may also be operated either neutral or it may beconnected to the shield screen 38 and thus operated at the samepotential as this screen. The top screen 42 may be connected to theshield screen 38 to be operated at the same potential as the screen.

A schematic representation of the tube 10 and a typical circuit foroperating it is shown in Fig. 2. In the circuit, the appropriate cathodenumbers 22 are shown connected together in pairs, the pairs, in thisinstance, comprising zero and one, two and three, four and five, six andseven, eight andnine. The circuit also includes a selector switch 44having five fixed switching elements or contacts 46 and a'movablecontactor 48 adapted to engage any of the fixed contacts. The selectorswitch may be a mechanical or electronic switch controlled or drivenfrom a keyboard, from a circuit matrix; associated with a counter, or itmay be driven in any other suitable manner. Each pair of cathodes'isconnected to one fixed contact of the switch 40. Each anode 36 and 40 iscoupled to a suitable positive DC. power supply in the range of about100 volts to about 300 volts. The shield screen 38 may be biased fromground to about 100 volts positive.

In operation of the circuit of Fig. 2, as each pair of cathodes 22 isconnected into an active circuit by the contactor' 48, one of thecathodes of each pair glows, depending on whi h a od is en g y t ccathodes 22', anodes 36' and 40' and a shield 38.

4 Thus, the even-number cathodes glow when anode 40 is energized, andthe odd-number cathodes glow when anode 36 is energized.

A typical binary-coded decimal counter system 49 in which the tube 10may be employed is shown in block diagram in Fig. 3. Thec'ounter shownincludes four flipflop circuits 50, 52 54, 56. connected to provide atypical counting operation. Input pulses are fed into the firstflipi-fiop. circuit 50, and the output of thefirst fiip-fiop' isconnected both intothecountingchain and to the anodes 36 and 40 of thetube 10. The output lines of the flip-flop circuits 52,54, and 56 arefed into a suitable selector matrix 58where the numerical count isdetermined and the output of the matrix is applied tothe' proper cathodeof the tube. Thus, in essence, the output of the matrix energizes aparticular cathode in a pair and the flip-flop 50 energizes a particularanode so that the proper cathode of the pair is ignited.

The principles of the invention may also be embodied in a tube whichincludes more than two sections or groups of electrodes. Such a tube 10'is shown schematically in Fig. 4 and comprises, in effect, two tubes ofthe type shown in Fig. 1 in the same envelope. The tube 10' com prisesone set of electrodes 60 including the electrodes shown in Fig. 2 and asecond set of electrodes 62 which may be arranged similarly to the firstset and includes The tube 10' may be operated so that one cathode ineach set glows at the same time and, thus, a two-numeral readout isachieved.

What is claimed is:

1. An indicator tube comprising a first indicator cathode adapted toglow and a second indicator cathode adapted to glow, an anode associatedwith each of said cathodes, and a shield electrode between each of saidcathodes and its associated anode.

2. The tube defined in claim 1 wherein all of the electrodes are alignedin a common stack.

3. The tube defined in claim 1 wherein said cathodes are electricallyconnected.

4. An indicator tubecomprising a-first group of indicator cathodesadapted to glow and a second group of indicator cathodes adapted to'glow, an anode associated with each of said groups of cathodes, and ashield electrode between each of said groups of cathodes and itsassociated anode.

5. The tube defined in claim 4 wherein all of the electrodes areoriented parallel to each other and aligned in a common stack.

6. An indicator tube comprising a first stack of indicator cathodesadapted to glow, an anode electrode at the top of said first stack, asecond stack of indicator cathodes adapted to glow, an anode electrodeat the bottom of said second stack, said stacks being aligned with eachother, and a shield electrode between said anodes.

7. The tube defined in claim 6 and wherein each cathode in said firststack is electrically connected to a cathode in said second stack. v I

8. An indicator tube comprising a plurality of electrode assemblies,each of said assemblies including a first indicator cathode adapted toglow and a second indicator cathode adapted to glow, an anode associatedwith each of said cathodes, and a shield electrode between each of saidcathodes and its associated anode.

References Citedin the file of this patent UNITED STATES PATENTS2,142,106 Boswau Jan. 3, 1936 2,606,309 Townsend Aug. 5, 1952 2,717,334Desch Sept. 6, 1955 2,756,366 Maynard July 24, 1956 2,769,939 WilliamsNov. 6, 1956 2,790,110 ,Applegate Apr. 23, 1957

